﻿using System;

class Program {
    static long Fibonacci(long n) {
        if (n <= 1) return n;
        return Fibonacci(n - 1) + Fibonacci(n - 2);
    }

    static void Main() {
        Console.Write("请输入要计算的 Fibonacci 数字: ");
        long n = long.Parse(Console.ReadLine());
        Console.WriteLine(Fibonacci(n));
    }
}
